Congenital anomalies of the kidney and urinary tract (CAKUT)
CAKUT เป็นกลุ่ม congenital anomalies ของ kidney + urinary tract
คิดเป็น ~20–30% ของ prenatal
anomalies ทั้งหมด
อาจเป็น:
- unilateral
หรือ bilateral
- isolated
หรือ syndromic
- coexist
หลาย anomaly ในคนเดียวกันได้
Clinical significance
CAKUT เป็นสาเหตุของ:
- CKD/ESKD
ในเด็ก ~30–50%
Poor prognosis โดยเฉพาะ:
- bilateral
disease
- reduced
nephron number
- small
kidneys/hypodysplasia
Embryology (high-yield)
Kidney development 3 stages
1. Pronephros
- week
4
- rudimentary/nonfunctional
- ต้อง involute เพื่อให้ kidney พัฒนาปกติ
2. Mesonephros
- temporary
urine production
- contributes
to bladder/genital tract
3. Metanephros
future permanent kidney
ประกอบด้วย:
- metanephric
mesenchyme
- ureteric
bud
เริ่มทำงาน:
- 6–10
weeks embryogenesis
Important developmental concept
Interaction ระหว่าง:
- ureteric
bud
- metanephric
mesenchyme
→
nephron + collecting system formation
Gene สำคัญ:
- RET/GDNF
- PAX2
- WT1
- EYA1
- HNF1B
- SIX1
- SALL1 ฯลฯ
Pathogenesis ของ CAKUT
เกิดจาก:
1.
genetic defect
2.
environmental teratogen
3.
abnormal migration
4.
collecting system maldevelopment
Genetics
~20% ของ CAKUT มี monogenic
cause
Associated genes:
- PAX2
→ renal-coloboma
syndrome
- EYA1/SIX1
→ BOR syndrome
- HNF1B
→ renal cyst +
diabetes
- RET/GDNF
→ renal agenesis
Environmental causes
สำคัญ:
- ACE
inhibitors
- ARBs
- vitamin
A deficiency
- teratogens
ACEI/ARB embryopathy:
- oligohydramnios
- renal
dysplasia/tubular dysgenesis
Epidemiology
Incidence:
0.3–1.6 ต่อ 1000 births
Most common antenatal finding:
- hydronephrosis
/ upper urinary tract dilatation
~30% associated with extrarenal anomalies
Kidney parenchymal malformations
1. Renal hypoplasia
นิยาม:
- nephron
น้อย
- structure
ปกติ
Diagnosis:
- kidney
size <2 SD
- DMSA
(99mTc-dimercaptosuccinic acid) radionuclide scan exclude scarring
2. Renal dysplasia / hypodysplasia
Pathology
- malformed
nephron
- disorganized
tissue
- cartilage/bone
metaplasia possible
Ultrasound findings
- echogenic
kidney
- poor
corticomedullary differentiation
- cysts
Clinical features
- antenatal
diagnosis common
- bilateral
disease → neonatal
renal failure possible
- associated:
- VUR
- hydronephrosis
- megaureter
- duplicated
system
Evaluation
อาจต้อง:
- VCUG
(voiding cystourethrography)
- DMSA
scan
- renal
function assessment
Prognosis
Unilateral disease
มักดีถ้า contralateral kidney ปกติ
Risk long-term
- hypertension
- CKD
- proteinuria
Follow-up:
- yearly
BP
- urinalysis
- creatinine
if abnormal
3. Multicystic dysplastic kidney (MCDK)
- nonfunctioning
dysplastic kidney
- multiple
cysts
- antenatal
detection common
ส่วนใหญ่ unilateral และ asymptomatic
4. Unilateral renal agenesis
Definition
Congenital absence of kidney
Incidence:
0.04–0.05%
Associated anomalies
~1/3 มี associated CAKUT
Most common:
- VUR
Extrarenal anomalies:
- cardiac
- genital
- GI
- skeletal
anomalies
Syndromic clues
BOR syndrome
- hearing
loss
- branchial
cleft anomalies
- renal
aplasia
Genes: - EYA1
- SIX1
Renal-coloboma syndrome
- optic
coloboma
- renal
hypoplasia
Gene: - PAX2
Evaluation of solitary kidney
Ultrasound
สำคัญที่สุด:
- kidney
size
- compensatory
hypertrophy
- search
ectopic kidney
VCUG
บางคนทำเพราะสัมพันธ์กับ VUR
Urinalysis
หา:
- proteinuria
Long-term risks of solitary kidney
Risk:
- hyperfiltration
injury
- CKD
- HTN
- proteinuria
Risk factors:
- obesity
- small
solitary kidney
- absent
compensatory hypertrophy
Follow-up solitary kidney
If compensatory hypertrophy present
- serial
US early life
- periodic
BP + UA until puberty
No compensatory hypertrophy
- yearly
BP + UA
- monitor
CKD closely
Renal tubular dysgenesis (RTD)
Severe disorder:
- absent
proximal tubules
- refractory
neonatal hypotension
- anuria
- oligohydramnios
- Potter
sequence
Causes:
- ACEI/ARB
exposure
- RAAS
gene mutations
US:
- kidneys
may appear normal
Mortality สูงมาก
Genetic cystic diseases
ARPKD
Gene:
- PKHD1
Features:
- collecting
duct cysts
- oligohydramnios
- pulmonary
hypoplasia
- HTN
- liver
disease
- renal
failure
ADPKD
Genes:
- PKD1
- PKD2
Features:
- bilateral
enlarged cystic kidneys
- usually
adult onset
- some
neonatal severe forms
Nephronophthisis
Features:
- tubular/interstitial
fibrosis
- corticomedullary
cysts
- progressive
CKD
Anomalies of migration
Pelvic kidney / horseshoe kidney
Usually asymptomatic
Complications:
- UTI
- obstruction
- stones
- VUR
Malrotation
Usually incidental
Associated:
- UPJ
obstruction
- nephrolithiasis
Collecting system anomalies
Examples:
- UPJO
- megaureter
- ectopic
ureter
- ureterocele
- VUR
- posterior
urethral valve
Duplex collecting system
Most common urinary tract anomaly
Complete duplication
- 2
ureters
- ectopic
insertion possible
Complications:
- obstruction
- VUR
- incontinence
Key clinical pearls
- CAKUT
เป็นสาเหตุสำคัญของ pediatric CKD/ESKD
- Prenatal
hydronephrosis คือ antenatal CAKUT ที่พบบ่อยที่สุด
- Solitary
kidney ต้อง long-term follow-up
- Compensatory
hypertrophy = favorable prognostic sign
- ACEI/ARB
exposure during pregnancy สามารถทำ severe fetal renal
injury ได้
- Bilateral
renal dysplasia/agenesis →
oligohydramnios + pulmonary hypoplasia
- CAKUT
มักมี associated syndromic/extrarenal anomalies ควรตรวจระบบอื่นเสมอ
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